Prehung interior door
2x4s for framing
2x lumber and 1/2" plywood, as needed for header
Safety goggles
Hammer
Nails
Power drill/driver
Drywall, drywall screws, and finishing equipment
Framing square
Cross brace
Spirit level
Wood shingle shims
Power miter saw or miter box and handsaw
Trim and finishing nails
Wood glue
Lockset
Screwdriver
Interior doors are often bought prehung, that is, the door is hinged and installed into its frame and all you have to do is install the unit into a rough opening. Most prehung doors come with complete installation instructions, including the rough opening size needed for that door. The prehung door unit shown below is being installed in a nonload-bearing wall. When ordering a prehung door, you have the choice of a right- or left-hand swing as well as having the factory drill the holes in the door for the lockset.
If the unit comes from the supplier with at least one cross brace to keep the door and frame aligned, leave the brace on until the door unit is plumbed, shimmed, and nailed into place. On partition walls that do not bear structural loads, use a header or 2x4s on the flat across the top of the opening. Load-bearing walls require a structural header. On each side of the opening, install one full-height stud and a shorter (jack) stud to help support the header.
1.
Frame the Opening for the Door
To fit an interior door into a nonload-bearing partition, lay out the rough opening, allowing for two jack studs. A jack stud nailed onto a full-height stud helps to support the header. Pack out vertically set headers with 1/2-inch plywood. (Fig. 1)
2.
Install Drywall
With the door framing in place, install drywall panels (typically 1/2-inch thick) using wide-threaded drywall screws. (Fig. 2)
3.
Check the Prehung Door for Square
Although this prehung door is hinged in its frame, it pays to check for square and lock the position with a cross brace. Position a framing square at one corner; once the corner is squared, nail the cross brace in place to hold that position. Both ends of the cross brace should extend beyond door unit. (Fig. 3)
4.
Position the Door in the Opening
Tip the door into place and hold it temporarily by wedging wood shingles as shims between it and the framing. The cross brace keeps the frame flush with the drywall. You might need a helper to assist you in lifting and positioning the door unit. (Fig. 4)
5.
Fasten the Door
Working from the inside of the wall, use more shingle shims and a spirit level to plumb the door in the framed opening. When the door is plumb, drive 10d finishing nails through the jamb and shingle shims into the 2x4 wall framing. (Fig. 5)
6.
Install the Trim
Select trim for the outside face that matches other trim in the room. Cut mitered corners, add glue, and nail the trim in place. (Fig. 6)
7.
Install the Lock
It's wise to order the door predrilled with holes for a lockset. You can buy the hardware you like and fasten it easily into the factory-drilled holes, referring to the instructions that accompany the lockset. (Fig. 7)
